BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Prevayler          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message Harri Vartiainen Guest Posted: Sun Dec 14, 2003 12:57 pm    Post subject: Prevayler Hello all, I came across "Prevalance layer for Java" ([url]http://www.prevayler.com)[/url], which looks very interesting. Does any similar projects exist for Delphi already? There seems to be one in Source Forge, but it looks pretty dead and hasn't produced any files. Back to top Eric Hill Guest Posted: Sun Dec 14, 2003 7:36 pm    Post subject: Re: Prevayler I haven't seen any Delphi-centric implementations of Prevayler, but here are my biggest concerns: 1) The database is purely OO, which means all reports, third-party integration, and front-end applications /must/ be custom-written. 2) The database is always in-memory, so restarting the db server forces you to reload several gig from the disk into memory (all the objects). While this might not take a long amount of time, it's quicker for a database engine to start up and request data from the disk as needed. 3) No native Delphi implementation :) Eric Back to top Harri Vartiainen Guest Posted: Mon Dec 15, 2003 7:38 am    Post subject: Re: Prevayler Eric Hill wrote: Quote: I haven't seen any Delphi-centric implementations of Prevayler, but here are my biggest concerns: 1) The database is purely OO, which means all reports, third-party integration, and front-end applications /must/ be custom-written. That's not a problem, there a lot of applications which do this anyway. Of course reporting etc must be done then manually.. Quote: 2) The database is always in-memory, so restarting the db server forces you to reload several gig from the disk into memory (all the objects). While this might not take a long amount of time, it's quicker for a database engine to start up and request data from the disk as needed. Not all applications have several gigs of data to handle. Prevayler system could be helpful to less-data-centric applications, which uses database only to store some static data and / or there is some kind of reasonable upper limit for size of data. Quote: 3) No native Delphi implementation I know, that's why I was asking ;) Back to top Franz-Leo Chomse Guest Posted: Mon Dec 15, 2003 10:38 am    Post subject: Re: Prevayler On Sun, 14 Dec 2003 14:57:14 +0200, Harri Vartiainen <harriv-bor (AT) prosys (DOT) fi> wrote: Quote: Hello all, I came across "Prevalance layer for Java" ([url]http://www.prevayler.com)[/url], which looks very interesting. The major limitation is that you have to have at least two independent copies of the prevayler system running at the same time. You can run two Java runtime environment on the same machine, but as the Delphi runtime is the OS itself, you either need a real network, or several virtual PC running. Regards from Germany Franz-Leo Back to top Harri Vartiainen Guest Posted: Mon Dec 15, 2003 12:29 pm    Post subject: Re: Prevayler Franz-Leo Chomse wrote: Quote: The major limitation is that you have to have at least two independent copies of the prevayler system running at the same time. You can run Why's that? I didn't find anything like that from the website. Back to top Franz-Leo Chomse Guest Posted: Mon Dec 15, 2003 1:15 pm    Post subject: Re: Prevayler On Mon, 15 Dec 2003 14:29:53 +0200, Harri Vartiainen <harriv-bor (AT) prosys (DOT) fi> wrote: Quote: Franz-Leo Chomse wrote: The major limitation is that you have to have at least two independent copies of the prevayler system running at the same time. You can run Why's that? I didn't find anything like that from the website. The server has to run in an independent runtime environment, since the first one can be stopped together with the major application(client). Regards from Germany Franz-Leo Back to top Harri Vartiainen Guest Posted: Mon Dec 15, 2003 2:41 pm    Post subject: Re: Prevayler Franz-Leo Chomse wrote: Quote: The server has to run in an independent runtime environment, since the first one can be stopped together with the major application(client). I don't understand your argument. What is server and what is client in this case? According to my knowledge (acquired from www.prevayer.org , Prevayler application can be just single application. Back to top Eric Hill Guest Posted: Mon Dec 15, 2003 6:31 pm    Post subject: Re: Prevayler Quote: 1) The database is purely OO, which means all reports, third-party integration, and front-end applications /must/ be custom-written. That's not a problem, there a lot of applications which do this anyway. Of course reporting etc must be done then manually.. It's a problem in my world because many of my customers like to write their own reports and don't get the application source :) Quote: 2) The database is always in-memory, so restarting the db server forces you to reload several gig from the disk into memory (all the objects). While this might not take a long amount of time, it's quicker for a database engine to start up and request data from the disk as needed. Not all applications have several gigs of data to handle. Prevayler system could be helpful to less-data-centric applications, which uses database only to store some static data and / or there is some kind of reasonable upper limit for size of data. Agreed. A smaller system should be fine. Quote: 3) No native Delphi implementation :) I know, that's why I was asking :P Eric Back to top Dirk Guest Posted: Wed Dec 24, 2003 1:03 am    Post subject: Re: Prevayler "Harri Vartiainen" <harriv-bor (AT) prosys (DOT) fi> schreef in bericht news:3fdc5e1c$1 (AT) newsgroups (DOT) borland.com... Quote: Hello all, I came across "Prevalance layer for Java" ([url]http://www.prevayler.com)[/url], which looks very interesting. Does any similar projects exist for Delphi already? There seems to be one in Source Forge, but it looks pretty dead and hasn't produced any files. There's no Delphi version. There is a .Net version though: Bamboo.Prevelance: http://bbooprevalence.sourceforge.net/ I tested it with C# and VB.net and I like it *very* much. I guess the reason why there is no Delphi version is the lack of proper serialization and/or reflection in Delphi. At least that's what stopped me from trying to port it to Delphi. With D8 (for .net) it should work fine. -- Kind regards, Dirk Back to top Dirk Guest Posted: Wed Dec 24, 2003 1:08 am    Post subject: Re: Prevayler "Harri Vartiainen" <harriv-bor (AT) prosys (DOT) fi> schreef in bericht news:3fddc800$1 (AT) newsgroups (DOT) borland.com... Quote: Franz-Leo Chomse wrote: The server has to run in an independent runtime environment, since the first one can be stopped together with the major application(client). I don't understand your argument. What is server and what is client in this case? According to my knowledge (acquired from www.prevayer.org , Prevayler application can be just single application. Correct. The changelogs (deltas) are 'played back' when the application reloads. You can also take snapshots of the 'database' at any point in time. -- Kind regards, Dirk Andries Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi OO design All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.